A method of manufacturing half-split bearings is conventionally known from Japanese Patent Publication No. 56- 41342. In the known method, an elongated strip that is material of the half-split bearing is fed into a press in a stepwise manner longitudinally of the strip. The press is actuated each time the strip makes a step forward, to successively cut the strip widthwise into a plurality of blanks different from each other. These blanks are pressed to manufacture half-split outer bearing plates.
The above known method has the following problems:
1) A strip-like plate to be fed into the press is required to be cut into a length substantially equal to a peripheral length of half-split bearing. Alternatively, the strip-like plate is required to be cut within the press. By this reason, there occurs abatement or chips. Thus, the yield is low.
2) Contiguous blanks chamfered by embossing are cut along V-shaped grooves, each pair of which are opposed to each other. Accordingly, each cut surface is brought to a configuration accompanied with a broken surface. This is inferior in appearance. Further, when a half-split bearing formed from the blank is assembled into an engine, there is a fear that fine or minute particles fall from the cut surface.
3) The process in which each cut blank is forced into a half-cylindrical coining die by a bending punch relies only upon friction of a minute surface of the cut blank which is brought into contact with the half-cylindrical coining die. Therefore, there is a fear that the blank shifts due to unbalance of friction.
4) In the aforesaid process, the blank tends to be lifted from the top of the bending punch when the bending processing proceeds to the middle, so that the blank is brought to a radius smaller than that of the bending punch. The forming proceeds as it is, and the blank is again brought to a configuration identical with that of the bending punch. Thus, undue force is applied to the bearing alloy.
Another prior art process is illustrated by FIGS. 6-12. In FIG. 6 it is seen that blank 45 is restrained in a width-wise direction by die 42, but the blank is not restrained at its central portion in a wall-thickness-wise direction. Thus, as shown in FIG. 7, when bend punch carrier 43 forces the bend punch 44 to reshape the blank 45, the blank becomes excessively bent because the central portion of the blank 45 is not restrained in the wall thickness wise direction, and this will often produce a crack or cracks in the bent blank 45. Also, a gap 46 will often be produced between the bend punch and the bent blank 45 as shown in FIG. 8.
The prior art process is continued in FIG. 9 with the bend punch 44 forcing the blank 45 into the die 42 to complete shaping of the blank, this step also often producing a crack or cracks in the blank. The prior art process is complete as shown in FIGS. 10 and 11 with the lifting of the bend punch carrier 43 and the removal of the finished product 45 from the bend punch 44 by means of the fingers 41. This prior art process often leaves the produce with undesirable cracks in its central position.